# What happen to \mathcal (IEEE conf. sample)

I am a beginner in Latex. I used to use \mathcal, for example:

# old code

\documentclass[12pt]{article}
\usepackage{graphicx}
\usepackage{amsmath}
\begin{document}
$\mathcal{C}$
\end{document}


### Output

I utilize the tex. sample from IEEE (open it with the original software):

I use the same code; however, I got this:

How do I fix it? (I want the previous one.)

• Welcome to TeX.SX! Can you please modify your sample document to use the precise setting with the ieeeconf class? – egreg Jun 13 '15 at 22:32
• I am not sure how to do it. I just use TEX to open it, and type the article. – sleeve chen Jun 13 '15 at 22:35
• I find this article; however, I cannot still fix it. tex.stackexchange.com/questions/120065/… – sleeve chen Jun 13 '15 at 22:37
• If I add $\mathcal{C}$ in sample.tex, I get the first “C”, not the second one. – egreg Jun 13 '15 at 22:39
• When I execute the sample.tex, there are two errors. After fixing it, I get the same results (the second one). I guess is there any other problem in my software? I can get the first one in other file instead of the IEEE ones – sleeve chen Jun 13 '15 at 22:48

It seems to be hard-coded in ieeeconf.cls. It loads mathptmx by default and as a result, \mathcal calls \mathrsfs. You can circumvent the problem loading newtx, which loads TeX Gyre Termes, another Times-clone:

\documentclass[12pt]{ieeeconf}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\usepackage{amsmath}
\usepackage{newtxtext, newtxmath}

\begin{document}

Lalala…
$\mathcal{C}$

\end{document}